Method of preparing thiazoles



Patented May s, 1928.

' UNITED STATES PATENT OFFICE.

LORIN B. SEBRELL AND JAN TEPPEMA, OF AKRON. OHIO, ASSIGNORS TO THE GOOD- YEAR TIRE & RUBBER COMPANY, OF AKRON, OHIO, A CORPORATION OF OHIO.

METHOD OF PREPARING THIAZOLES.

No Drawing.

Our invention relates to the preparation of mercaptothiazoles and it particularly pertains to that class of the above designated materials which embodies in its structure an aryl group or substituted derivative thereof.

The object of this invention is to provide a new method of preparing mercaptothiazoles.

Briefly, the invention consists in reducing ortho-nitro-halide compounds with a soluble basic hydro-sulfide such for exampleas the atives are known; of these might be mentioned the treatment of a substituted thiourea with sulfur under pressure and the preparation involving the reaction of an ar 1 amine, carbon bisulfide and sulfur. Tie present method is characterized as one which utilizes'cheap raw materials and re quires little or no expensive equipment in securing the reaction. Moreover, a good yield may be had even when the reaction is effected at relatively. low temperatures and, in addition, a water solution maybe employed thereby obviating the necessity of costly solvents.

The preparation of Q-mercaptobenzotlnazole may be taken as characteristic, for purposes of illustrating the application of the principles of our invention.- One hundred parts of ortho-nitro-chlorbenzene are suspended in a water solution of two hundred fifty parts of sodium sulfite, previously saturated with hydrogen sulfide. The mixtureis warmed slightly and hydrogen sulfide, which is saturated with carbon bisultide, is passed through the solution. Ye have found that a ninety per cent yield is obtained when the reaction is carried out at atmos heric pressure, a nd between 60 and 90 In order to reduce the time of reaction, however, a positive pressure of the Application filed June 17, 1925. Serial No. 37,861.

gaseous materials which may aggregate 250 pounds per square inch and .an elevated temperature which even exceeds 150 C. ma be employed. In the latter case, the yie d is somewhat impaired although the t1me necessary to complete the reaction is materially reduced. Subsequently the reacted mixture is steam distilled to remove undesirable by-products or raw materials, after which the charge is acidified. The precipitated product thus formed is relatively pure, but by extracting with dilute alkali and reprecipitating, the comparatively pure mercaptan is obtained.

Although we specify that carbon bisulfide be added with the hydrogen sulfide, this is not entirely necessary as it may be added in liquid form if so desired. Furthermore, it

will be appreciated that, while we have specifically named sodium sulfide, any soluble basic sulfide, or b drosulfide will suifice.

The reaction is probably as follows:

N O: NO 2 NQSH C1 SH O-nitro-ehlorbenzene O-nitro-thiophenol N0: NH:

' O-amino-thiophenol NHa N cs, H S

C-SH HzS '2-mcrcaptobenzothiazole is obtained in about five hours. The steps involved in its purification need not "aga n be discussed. This alternative method comes clearly within the provisions of the present invention as will be readily appreciated by comparing the re- S S SH a b c N0: N N

' SH I S\ US: C-SH+H1S O NH: O

2-mercaptobenzothiazole The final product is designated in accordance with the recognized authorities on chemical nomenclature.

The examples herein above set forth have been specific to the phenyl derivative, however, the characteristic of the raw materials essential to its successful utilization is that the nitro grou and the chlorine or sulfur atom be attac led to the adjacent carbon atoms. We therefore do not limit ourselves to hexa-cyclic structures but contemplate both open chain and rina structures which are so characterized. ferhaps the best known examples are the ortho-nitro-arylhalides.

Although we have disclosed but a single embodiment of the principles of our invention, together with a sli ht modification thereof, it will be appreciated by anyone skilled in the art that the may be extended to a large class of materia s which are known to react in a manner analogous to the phenyl compound and that any of the intermediate products designated in the above reactions may be substituted for the original materials. Furthermore, while a set of reacting conditions have been specifically set forth, it is obvious that they are merely exemplary and that many variatlons may be made without departing from the scope of the invention. We desire, therefore, that only such limitations shall be imposed as are consistcut with the prior art and the appended claims.

What we claim is:

1. A method of preparing mercaptothiazoles which comprises causing a material NazSn having a nitro and halogen radical attached to adjacent. carbon atoms to react with a solution of a basic sulfide in the presence of carbon bisulfide and hydrogen sulfide.

2. A method of preparing mercaptothiazoles that comprises causing an ortho-nitrochlorbenzene material to react with a dissolved basic sulfide in the presence of carbon bisulfide and hydrogen sulfide.

3. A method of preparing an aryl-mercaptothiazole that comprises causing the corresponding ortho nitro-aryl-halide material to react with a solution of a basic sulfide in the presence of hydrogen sulfide and carbon bisulfide.

'4. A method of preparing an aryl-mercaptothiazole that comprises causing the corresponding orthonitro-aryl-halide material to react, under the influence of positive pressure and elevated temperature not to exceed the decomposition point of the product, with a solution of a basic sulfide in the presence of hydrogen sulfide and carbon bisulfide.

5. A method of preparingan aryl-men captothiazole that comprises causing the corresponding ortho-nitro-ar l-halide material to react with an alka ine h drosu1- fide in the resence of carbon bisul de.

6. A met 0d of preparing 'aryl-mercaptothiazoles that comprises causing an orthonitro-arly-halide to react with a water solution of a. basic sulfide, carbon bisulfide and" hydrogen sulfide.

7. A method of manufacturing 2-mercaptobenzothiazole which comprises causing orthomitro-chlorbenzene to react with a water solution of a basic sulfide in the pres- (fairace of hydrogen sulfide and carbon bisul- 8. A method of manufacturing 2-mercaptobenzothiazole which comprises, causing ortho-nitro-chlorbenzene to react, under positive pressureand elevated temperature, with a water solution of a basic sulfide 'in the resence of hydrogen sulfide and carbon bisu fide.

9. In a method of preparing benzothiazoles from a raw material embodying a nitro group, that step which involves reducing the nitro derivative with a basic hydro sulfide in the presence of carbon bisulfide.

In witness whereof, we have hereunto- 

